Engine: introducing IGfxModeList interface

IGfxModeList is a simple interface providing means to enumerate through supported graphics driver modes.
Implementations available for Software and D3D9 graphics drivers.
Engine: rewrote automatic scaling filter selection

* New implementation is compatible with fullscreen mode;
+ Automatic selection can now be explicitly triggered by setting filter id to "max" in game config.
Windows: added "max" filter choice in winsetup